New engine knocking... so blown.

[DanMan2k06]

Some of you guys might have seen a thread or two of mine eluding to an engine rebuild or swap recently. Well I finally put it in over the weekend and started it up, and now it's knocking pretty bad. I'm really diappointed.

I used an Engine-Tech rebuild kit, bored .030" over. New EVERYTHING. Minus the connecting rods. New crank, new cam, new pistons, reman'd head, new lifters, rockers, pushrods, everything.

The first time I cranked it over, the distributor was indexed wrong. It took about three 10-second cranking sessions to realize ok, somethings wrong. Flipped it 180, it started right up. the lifters were loud for about 5 seconds as usual, but then quieted down to normal. However, a very audible knock did not go away. Almost sounds like a diesel. It's definitely not from the head or valve-train. You can hear it best if you stick your head in the driver's wheel well. It goes away once the RPM's climb but as soon as your drop back to 1000rpms or idle it's clear as day. Can be heard clearly in the cab when idling as well.

I used Rotella 10w-30 and 2 teaspoons of Lucas zddp additive for break-in. After she started I drove around town, varying rpms and load constantly, did 2 or 3 WOT rips, and changed the oil at 20 miles.

What do you guys think it could be? Main bearings? Wrist pin? It's DEFINITELY a knock. Not a tick or a ping or a mothereffin squawk, but a solid knock. Best description is someone holding two small blocks of wood and hitting them together.


Edit: Should be moved to OEM tech.

 

[gradon]

Could be the torque converter bolts. . .

 

[DanMan2k06]

That's what I immediately thought, but I torqued them all 3 times when I was under there. WITH a torque wrench. Flexplate definitely wasn't cracked when I had it out 2 days ago either. I'll check on the bolts again.

 

[DanMan2k06]

Just checked all the TC bolts, they're still tightened to spec. FML...

 

[Shorty]

are you sure the torque converter is fully seated in the transmission? I've heard them make a horrible knock when they're not fully seated.

If so, I'd say wrist pin or connecting rod bearing are gonna be the likely culprits. As much as I hate to troubleshoot on a fresh rebuild, you'll probably want to pull plug wires and determine what cylinder is the offender and get her outta there.

 

[Talyn]

Did you reinstall the cam pin and spring? How loud is this knock? What about the flexplate to crank bolts? Are you sure it is in the engine and not something external hitting something? Also, what did you do for the cam break in procedure?

 

[O-Gauge Steamer]

Just an FYI... If you stand the lifters, cup side up, in a thin (5W maximum) oil overnight, they will mostly fill. Manually pump them to finish pre-oiling them.

Two good things:
1. Stops the startup valve clatter.
2. Allows oil pressure to build faster.

If the lifters are dry at install, there will be a delay in oil pressure as they fill. Not my original idea. My Dad was doing this back in the 40's. Yah, I'm that old...

 

[Talyn]

Oh.. did you prime the engine oil before you started it?

 

[old_man]

Rather than talk, drop the pan and look. Buy some plastigage and check the tolerances. Did you plastigage the crank and rods before putting them in? Did you mike the rods and recondition as necessary?

If the crank and rods were turned, did you get the right set of bearings?

 

[DanMan2k06]

Crank was plastigage'd when installed, rods were mic'd. Crank was reman'd and turned .020 main and rod journals. all bearings were correct, I double checked that before installing everything. It's definitely only one cylinder making the noise, the frequency is pretty distinguishable at idle. For priming the engine oil I took out all the plugs, cranked it until the oil light went out, and re-installed them. However, this was before cranking it under compression with the distributor indexed wrong.

Cam was switched from the thrust plate design to the spring and pin design, and yes it was all installed correctly.

 

[Talyn]

Pull a each plug individually and see if the sound changes. At least that way you can see if it narrows it down to a particular cylinder. Does it happenw hen it is hot and cold?

Where is the thrust bearing located on the crank? Some people put them at the rear like a Chevy, which is wrong. It goes on the #3 spot. What is your crank end play?

 

[DanMan2k06]

I BELIEVE THE THRUST BEARING IS AT THE NUMBER 4 LOCATION? I DON'T REMEMBER OFF THE TOP OF MY HEAD, BUT I DO REMEMBER THAT IT COULD ONLY GO IN ONE SPOT. I'LL HAVE TO CHECK MY NOTES FROM LAST YEAR AND GET BACK WITH THE CRANK END PLAY NUMBERS.

A FEW GUYS HERE AT WORK THINK IT'S A WRIST PIN NOISE JUST BY MY DESCRIPTION. I REALLY DON'T HAVE A LOT OF EXPERIENCE WITH ENGINE INTERNALS (AS IF YOU COULDN'T TELL...). THEY SUGGESTED THAT IF IT WAS A SPUN BEARING IT WOULD BE A LOT LOUDER AND SOUND TOTALLY CATASTROPHIC. WHILE THIS IS A NOTICEABLE KNOCK, BY NO MEANS DOES THE MOTOR SOUND LIKE IT'S ABOUT TO GRENADE. IT HAPPENS HOT OR COLD, BUT DOES SEEM TO BE MORE APARENT WHEN IT'S WARMED UP. STILL RUNNING ROTELLA 10W-30 IN IT. I'M GONNA BRING IT DOWN HERE TONIGHT AND PULL THE PAN AND VALVE COVER.

Edit: apologies for the party caps, these work computers like to scream.

 

[Talyn]

Like I said, the thrust bearing goes at the #3 location, not #4. I have seen people put the thrust bearing at the rear on the 4.0L, so it is possible.

 

[DanMan2k06]

Dropped the pan. Everything looks good to the naked eye. Thrust bearing is on the third journal like you said. The oil doesn't have any ridiculous metal bits in it either. I kept a jar of it from the first 20 miles change as well, and it looks ok especially considering a first start-up. I'd love to think I'm over-reacting here, but damn the 2 other jeeps we have in the driveway sure don't sound like this... and they both have over 150k on them... I'm gonna drive it to work tomorrow and have a few of the real heavy gearheads take a look at it.

 

[wolfpackjeeper]

I am trying to remember, but I think my stroker sounded pretty funny for the first little bit. It took a little bit for one piston to seat its rings just right.

 

[DanMan2k06]

Is there a chance one of my lifters could be sticking or making noise? I forgot how far downinside the block those guys really are, so it may be a possibility. If so are they as easy as it seems to replace? Pull the head and drop some new ones in?

 

[Talyn]

Haver you tried pulling spark plugs and narrowing it down to a specific cylinder?

 

[DanMan2k06]

I did, and right as I got to number 2 it started raining and I couldn't distinguish anything. This is the first thing I'm gonna do tomorrow. It SOUNDS like it's around cylinders 4-6, but who really knows.

 

[GrimmJeeper]

take a piece of pipe and put it to your ear and move the other end around the engine bay and against the block next to each cylinder, that can help you narrow down where the noise is coming from. This works especially well for noisy lifters as they are right next to the passenger side of the block.

Might help you track down where the noise is coming from at least :dunno: I tend to agree with the previous post about either the torque converter not being fully seated on the input shaft of the trans, or the bolts holding the flex plate to the crank being loose - especially since you say the noise seems to be coming from the back of the engine. Have you tried running the engine with the inspection plate removed from the bellhousing to see if it gets louder?

 

[DanMan2k06]

Yea I actually have the inspection plate off now. There's no way the flexplate to crank bolts are loose. I distinctly remember torquing every one of those to it's ridiculous 105 ft/lb spec lol. How would the torque converter not be seated? Like it's crooked? All that's on the end of it is a little nub where the pilot bearing would be on a manual. And that went in no problem. I have today off so I'm gonna look around a lot, do the spark plug test, maybe unbolt and re-bolt the bellhousing, and pray that I find something that's not inside the crankcase.